@Psyco I was only pointing out the Arduino as an option. Yes , if you stick with some sort of signal coming via USB, you'll need to get usb pins 2 and 3 from your wifi transmitter connected to your stepper motor driver (and yes a shield will do it, as in http://www.circuitsathome.com/products-page/arduino-shields/usb-host-shield-2-0-for-arduino).

Once again, that's overkill. But in case you were hoping to connect the stepper motor to USB using analogue or logical pulses only, the ICs like nand-gate switches and buffers you'll need are already best used bundled into prototype stage circuit boards like Bssic Stamp, Pic and, best of all, Arduino. Once it works, you could look for something more elegant, (even a patent!)

@psyco

Arduinos are simple enough, however note that the standard library for the Arduino is blocking. Have a look at this library:

http://www.open.com.au/mikem/arduino/AccelStepper/

This will simplify stuff.

I used a similar approach on my crane head control:

http://personal-view.com/talks/discussion/comment/78784#Comment_78784

Do you need the follow focus to be wireless? If a cable is ok, use a servo and a cheap servo tester.

Servo controller

http://www.ebay.com.au/itm/Servo-Tester-3CH-ESC-Switch-CCPM-Consistency-Master-Checker-Indicating-Lamp-/300684584341?pt=AU_Toys_Hobbies_Radio_Controlled_Vehicles&hash=item460232a595

@goanna @andyharris @kavadni you really got me convinced that the Arduion route is the way to go ;-)

First I really have to check the USB back channel on my wireless system (how it responds to direct voltage pulses). But if thats turns out to need USB controller chips I will buy an Arduino package and learn how to programm it.

With the Arduino it will also be possible to controll the focus motor from a Laptop with preprogrammed focus points. Quite some work ahead, but looks interesting. Thanks for all your input.

PS: Stage 2 of my rig is nearly finished - hand held Steadycam system (vest and arm are stage 3).

Hey guys, after checking the USB back channel again, I'm sure it needs a USB host controller (as there was no simple on/off signal transmitted).

So, I will go the Arduino way.

Using an Arduino UNO and a www.iteadstudio.com Dual Step Motor shield 1.0 to controll a stepper motor from my Mac will be the first step. After that I will add a USB shield and incremental encoder to complete the package.

@kavadni a servo won't work, as it is loud and has only a very limited angle of rotation.

@andyharris thanks for the link to the stepper controll library - I hope it works with the iteadstudio shield?

All cool ideas, but what is the use of a servo FF when you can't use it on a sound take?

Well, having used microforce zoom controls when I was operating on arris (backinnaday), I became very used to controlling zoom that way. There used to be an Israeli company that made them cheaper than the $6K models. I don't think they are around any more...

psyco that rig is fantastic. I plan on building my own in the near future and any advice you can provide me with would be greatly appreciated. My brother is a mechanical engineering student so I have access to any machine I would need (CNC, lathe, drills etc.) But he's very busy with studies so he wouldn't be able to help much with the actual design/build.

You said you cut everything from solid aluminum blocks - how did you go about doing this? Some of those parts looks very complicated. Also, can you show me any resources (books, forums) you used for direction? Lastly, did you anodize the parts? I did some research yesterday and it seems to be a fairly simple project.

@dumile sorry, didn't see your post until now (don't add a space between @ and the name or I won't see it as a reply;-).

First: Be carefull, this professional machines are dangerous - you might loose an arm or be dead before you know what hit you. I would advise you to get your brother show you how everything is done properly and that he is allways near by, just in case.

Sorry, but I can't help you with books or forums. I had a basic training for about 3 month, starting with cuting steel by hand, drilling 10000000 holes, cuting threads, measuring,... all by hand or with small machines. Just after leraning all this (and getting some bleeding fingers) I learned about how to use the big machines. I had a dedicated teacher that would "explain" things to me. It wasn't hard for me to learn all this in such a short time (normally its done in about 2 years), as I have worked with wood for years (and I might have some talent for things like that;-).

I have also designed lots of other things/parts before. Its nothing you can learn from a book. You just have to try, make mistakes, try again and develop your own workflow. Technical drawings help a lot (thats something you can learn from a book, but that needs practice too). And its always a good idea to look how it has been done before - I got a lot of ideas from the Steadycam and Sachtler pictures on the internet.

After getting a first design of the whole system I start looking at the individual parts. I try to think it that way: 1) Whats the purpose of the part/what do i want it to do? 2) How will it look/how strong has it to be? 3) Does it fit into the rest of the project/Can I reach all screws when its in place? 4) Do I like its look/does it feel right? ....after doing that for every part, I start all over again till I'm sure I won't waste 100 hours on some parts that don't work;-) For the most complex parts and especially to test if they will fit with all other parts I used a 3D programm. I used Cinema 4D and in one case even made a stereoscopic video of some parts rotating to check if they really fit.

After all parts were designed and all technical drawings were finished, I startet cutting them. I just got some aluminium blocks from Ebay, a small milling machine (its normally only used to cut wood) and drilling machine from a store, and the cross table again from Ebay. It does make a horrible sound when cutting through a solid block of metall and is not really save (but I still have all fingers and eyes;-). First make a raw cut to just get some material out of the way. Second do a fine cut to get everything like planned. For aluminium you should work as precise as 0,05mm when parts have to fit into each other. If its no special part you still should be as precise as 0,2mm. Try to work as precise as possbile at the start, things will get worse by itselfe:-P

I didn't treat the raw aluminium parts in any way. It will get dull by itselfe after a some time. So, I will paint the whole rig black when everything is finished. But I still have to design and built the arm and vest and I don't have the time for it at the moment. And thanks to (fucking) Olympus I have to redesign the wireless focus unit first:-(

I hope there was at least a littel bit of usefull information in this very long text. Oh, and one thing - it was a very nice feeling after cutting/drilling/... for about 2 years when I could assemble the whole rig for the first time...very nice :-)))

@kazuo

And what do I want a small sensor kamera for? The rig is a steadycam system - no kamera has that built into it. Without that its a pretty small and lightweight camera/rig.

If you doing handheld homevideos, than I do agree that a Varicam or this rig is overkill - but thats not what I intend to do;-)

@Psyco

What are you getting out of yr small camera, regardless of the size of its sensor? 24, 28 mbps at best? The Varicam will give you AVC Intra 100 without batting an eyelid. If you are using any DSLR, you need to hack your camera to get there. Or better still, try an external recorder, and hope it yields very clean results without more work in post.

I came over to DSLR because I could no longer handle huge cameras because of back and shoulder pains. What are your reasons?

@psyco

I am not new. I have been doing film and media for 15 years. I don't profess to know alot, but I am not new ;) I started collecting Carl Zeiss and Leica lenses 10 years ago, and I have a substantial suite today, so i know abit about vintage glass.

IS GH2 the first and only camera you've used in your life?

All I was trying to point out to you and everyone who's reading is that sometimes it's not necessary to spend so much money pimping your camera in a certain way. An impressive looking rig will not make you a better cameraman. Even if you disagree, you dun have to be dismissive my friend.

@kazuo

I mean new, as new to this forum. And no, the GH2 is not my first camera.

And whats your point? Having no rig doesn't make me a better cameraman either. I built that rig because I can. It was fun (most of the time). And buying something that comes even close to this would have cost much more than I'm willing to spend. I spent about 1/100 of the cost of a Steadycam or Sachtler or Arri.

I wanted one piece of equipment to make shoots with camera movement - my decision was: camera stabiliser, because its the moste versatile option.

So, whats the problem? If you also want one - sorry - there is only this prototype;-)